Unit test in jwat-common fails occasionally when it should pass, due to ordering of results.

One of the tests in jwat-common occasionally fails, with this result:

test_contenttype(org.jwat.common.TestContentType): expected:
<application/http; [msgtype=request; charset=utf8]>
but was:
<application/http; [charset=utf8; msgtype=request]>

The test appears to be rejecting the test result due to the order of the mime-type attributes, but attributes are not order-sensitive and probably implemented by a Set under the hood. Sets do not guarantee ordering of entries so I would expect this test to fail 50% of the time.